Bhaskar Das

Bio: Bhaskar Das is an academic researcher from Assam University. The author has contributed to research in topics: Coercivity & Magnetism. The author has an hindex of 19, co-authored 101 publications receiving 1170 citations. Previous affiliations of Bhaskar Das include Jadavpur University & KIIT University.

Gold Nanozymes: From Concept to Biomedical Applications

Abstract: In recent years, gold nanoparticles have demonstrated excellent enzyme-mimicking activities which resemble those of peroxidase, oxidase, catalase, superoxide dismutase or reductase. This, merged with their ease of synthesis, tunability, biocompatibility and low cost, makes them excellent candidates when compared with biological enzymes for applications in biomedicine or biochemical analyses. Herein, over 200 research papers have been systematically reviewed to present the recent progress on the fundamentals of gold nanozymes and their potential applications. The review reveals that the morphology and surface chemistry of the nanoparticles play an important role in their catalytic properties, as well as external parameters such as pH or temperature. Yet, real applications often require specific biorecognition elements to be immobilized onto the nanozymes, leading to unexpected positive or negative effects on their activity. Thus, rational design of efficient nanozymes remains a challenge of paramount importance. Different implementation paths have already been explored, including the application of peroxidase-like nanozymes for the development of clinical diagnostics or the regulation of oxidative stress within cells via their catalase and superoxide dismutase activities. The review also indicates that it is essential to understand how external parameters may boost or inhibit each of these activities, as more than one of them could coexist. Likewise, further toxicity studies are required to ensure the applicability of gold nanozymes in vivo. Current challenges and future prospects of gold nanozymes are discussed in this review, whose significance can be anticipated in a diverse range of fields beyond biomedicine, such as food safety, environmental analyses or the chemical industry.

Novel Nanostructured Rare‐Earth‐Free Magnetic Materials with High Energy Products

Abstract: Novel nanostructured Zr2 Co11 -based magnetic materials are fabricated in a single step process using cluster-deposition method. The composition, atomic ordering, and spin structure are precisely controlled to achieve a substantial magnetic remanence and coercivity, as well as the highest energy product for non-rare-earth and Pt-free permanent-magnet alloys.

Facile bio-synthesis of gold nanoparticles by using extract of Hibiscus sabdariffa and evaluation of its cytotoxicity against U87 glioblastoma cells under hyperglycemic condition

Abstract: In the present paper, a facile synthesis of gold nanoparticles is reported with leaf and stem extract of Hibiscus sabdariffa . Structural features of as synthesized nanoparticles are characterized by UV–vis spectroscopy, XRD, FTIR, and XPS. Morphology of the above synthesized gold nanoparticles is investigated by electron microscopy. The stability of the nanoparticles is studied in different concentrations of glucose which suggested their possible application under hyperglycemic condition. As synthesized nanoparticles has shown selective toxicity towards U87 glioblastoma multiforme cell line under normal and hyperglycemic condition, indicating their potential to be used in the development of value-added products in the biochemical industries. The possible mode of activity of the above nanoparticles has been studied by in vitro molecular techniques.

Hf–Co and Zr–Co alloys for rare-earth-free permanent magnets

Abstract: The structural and magnetic properties of nanostructured Co-rich transition-metal alloys, Co(100-x)TMx (TM = Hf, Zr and 10 ≤ x ≤ 18), were investigated. The alloys were prepared under non-equilibrium conditions using cluster-deposition and/or melt-spinning methods. The high-anisotropy HfCo7 and Zr2Co11 structures were formed for a rather broad composition region as compared to the equilibrium bulk phase diagrams, and exhibit high Curie temperatures of above 750 K. The composition, crystal structure, particle size, and easy-axis distribution were precisely controlled to achieve a substantial coercivity and magnetization in the nanostructured alloys. This translates into high energy products in the range of about 4.3-12.6 MGOe, which are comparable to those of alnico.

Assembly of uniaxially aligned rare-earth-free nanomagnets

Abstract: We report HfCo7 nanoparticles with appreciable permanent-magnet properties (magnetocrystalline anisotropy K1 ≈ 10 Mergs/cm3, coercivity Hc ≈ 4.4 kOe, and magnetic polarization Js ≈ 10.9 kG at 300 K) deposited by a single-step cluster-deposition method. The direct crystalline-ordering of nanoparticles during the gas-aggregation process, without the requirement of a high-temperature thermal annealing, provides an unique opportunity to align their easy axes uniaxially by applying a magnetic field of about 5 kOe prior to deposition, and subsequently to fabricate exchange-coupled nanocomposites having Js as high as 16.6 kG by co-depositing soft magnetic Fe-Co. This study suggests HfCo7 as a promising rare-earth-free permanent-magnet alloy, which is important for mitigating the critical-materials aspects of rare-earth elements.

Recent biomedical applications of gold nanoparticles: A review.

Abstract: Recent advances in nanotechnology are as a result of the development of engineered nanoparticles. Efficiently, metallic nanoparticles have been widely exploited for biomedical application and among them, gold nanoparticles (AuNPs) are highly remarkable. Consequent upon their significant nature, spherical and gold nanorods (Au NRs) nanoparticles attract extreme attention. Their intrinsic features such as optical, electronic, physicochemical and, surface plasmon resonance (SPR); which can be altered by changing the characterizations of particles such as shape, size, aspect ratio, or environment; ease of synthesis and functionalization properties have resulted to various applications in different fields of biomedicine such as sensing, targeted drug delivery, imaging, photothermal and photodynamic therapy as well as the modulation of two or three applications. This article reviewed the popular AuNPs synthesis methods and mentioned their established applications in various demands, especially in biological sensing.

Desk handbook phase diagrams for binary alloys

Abstract: Get the phase diagram information you need at a price you can afford. Key Features: Peer reviewed by the Japanese Committee for Alloy Phase Diagrams. Updated through April 2000. Total number of diagrams = 2,332 (605 are new of greatly revised diagrams; among these 171 are not in Binary Alloy Phase Diagrams, 2nd Edition). Approximately 600 crystal structure tables of systems for which phase diagrams are unknown. You've been asking for a simple book containing just binary phase diagrams and crystal structure data. Desk Handbook: Phase Diagrams for Binary Alloys meets this need, and it presents the most current information. Updates the previous print compilation of binary phase diagrams by 10 years. Presents diagrams in consistent size. Shows the principal axis in atomic per cent, with a secondary axis in weight per cent. Includes an introductory article on phase diagrams and their use. Gives reference to the original literature source. This volume is the latest outgrowth of the phase diagram activity in which ASM International has been involved since 1978.

Gold Nanoparticles for Photothermal Cancer Therapy.

Abstract: Gold is a multifunctional material that has been utilized in medicinal applications for centuries because it has been recognized for its bacteriostatic, anticorrosive, and antioxidative properties. Modern medicine makes routine, conventional use of gold and has even developed more advanced applications by taking advantage of its ability to be manufactured at the nanoscale and functionalized because of the presence of thiol and amine groups, allowing for the conjugation of various functional groups such as targeted antibodies or drug products. It has been shown that colloidal gold exhibits localized plasmon surface resonance (LPSR), meaning that gold nanoparticles can absorb light at specific wavelengths, resulting in photoacoustic and photothermal properties, making them potentially useful for hyperthermic cancer treatments and medical imaging applications. Modifying gold nanoparticle shape and size can change their LPSR photochemical activities, thereby also altering their photothermal and photoacoustic properties, allowing for the utilization of different wavelengths of light, such as light in the near-infrared spectrum. By manufacturing gold in a nanoscale format, it is possible to passively distribute the material through the body, where it can localize in tumors (which are characterized by leaky blood vessels) and be safely excreted through the urinary system. In this paper, we give a quick review of the structure, applications, recent advancements, and potential future directions for the utilization of gold nanoparticles in cancer therapeutics.